1. ## Do You know the answer?

Here is one for you that I have no idea how they got the answer. Would be interested to find out though.

An involved second floor measures 125 ft. wide by 175 ft. long with an approximate ceiling height of 10 ft. What is the approximate gallonage needed for the fire flow?

a. 1500
b. 2000
c. 2200
d. 2500

Does anyone know how to answer this? I can't find an explanation or formula anywhere.

Thanks,
Scottsfire

2. Hmmm...I don't know....the old length X width divided by 3 produces 7291.66, which isn't even close to any of the choices listed. Is this assuming 100% involvement?

3. the answer is c.2200. I got got 2188 with the Iowa State University formula (cubic feet involved/100=gpm required

4. Saylesville..........that is the correct answer according to the answer key but didn't know how the arrived at that answer. I'm assuming that this formula is taught in Delmars Pump book but I searched high and low in IFSTA and couldn't find anything!

Why is it called the Iowa State Formula.......did they think of it first?

Hey....thanks man I appreciate it.

Scottsfire

PS. Dmleblanc.....I kinda familiar with the formula you are using but isn't it "length x width x height= A then A is divided by 3" or am I wrong in adding the height in there?

5. I don't want to jump in on Dmleblanc, but I believe he is talking about the NFA formula - L x W x # of floors divided by 3.

6. Spencer.......so needless to say this would be the calc for multistory buildings? If so, what is used on regular single story occupancies? I know there are a few out there but just wondering which would be most accurate........whats IFSAC going to want or use on their test?
Thanks,
Scottsfire

7. I was thinking of the DmLeblanc formula...........

8. Scott,

You can use the same formula for single story dwellings. If the building is single story and 40 x 20 the forumula would read:

40 x 20 x 1
____________

3

So for single stories, you just use 40 x 20 divided by 3, or for two stories, it would be:

40 x 20 x 2
___________

3

9. Spencer,
I see........now it makes since.
Thanks for the info......
There is so much knowledge in these forums.
Scottsfire

10. i know of about 6 different way to calculate fire flows each one will give a different gpm flow. Our department uses primarily the NFA quick calc method (LxWx# of floors/3) which was designed for the officer of the first engine on scene to find the fire flow with little math. This way is clearly not the way that the question wants you to do it.i will have to look throught my old school books to relearn how to do the other 5 methods.

11. Follow me on this one:

We can convert (Cubic Feet Involved / 100 gpm) into a "number of floors" version as follows:

CFI = L x W x H of involved area.

Assuming H = 10 ft. (residential), then we can reduce

(L x W x 10) / 100 to (L x W x 1) / 10

and this will work as (L x W x #floors) / 10, giving the same answer as CFI / 100 for residential structures.

If we assume 12 ft. floors for commercial structures, it becomes:

(L x W x #floors x 1.2) / 10, or approximately

(L x W x #floors) / 8 for commercial structures, such as office buildings.

To get (L x W x #floors) / 3, to be equivalent to CFI / 100, we need the floors to be approximately 33 ft. in height. This may be true for an industrial, warehouse or large retail building.

So, assuming CFI / 100 is the exact calculation, shouldn't the "quickie" calculations be:

(L x W x #floors) / 10 for residential

(L x W x #floors) / 8 for commercial

(L x W x #floors) / 3 for industrial/large commercial?

Any insights?

12. Bob,
I think i follow what you are saying. It makes sense to me, i think the way you are talking about is a more precise way. It takes into account that different structure types have different fuel loadings (like the Branigain(sp?) fire flow method) However and the is just my thought on the matter in order to keep it to a mental math level go with divided by three. To me this would be an easier calculation for the first officer onscene to do in his head when he is entering the fire block. The officer can see the building estimate the L and W, count the floors and, do the math in his head. this would enable the officer to get a some what close fire flow in his head to better understanding what fire flow he needs for the building. By dividing by three it limits the difference between the estimated L and W and the real L and W. Also it gives you the highest GPM flow to take into acount the estimated L and W. Any thoughts

13. It is the Iowa State formula, though I cannot tell you why it is called that.

The formula is LENGTH X WIDTH X HEIGHT divided by 100. That comes to about 2187, or 2200 GPM as the answer.

Just what Saylesville said. I had to restate it in terms I could understand to make myself feel better! Sorry.

14. Okay, I have my 'SpartanGuy' formula. It goes like this.

Judge what you have by your pre-existing knowledge of the building's fire load and bank on your experience as a line officer/pump operator/firefighter and pull the appropriate sized line. Take it to the seat of the fire and apply water to that location.

If it doesn't make much progress, call in another line of equal or greater size.

Just think and you don't have to play around with any math!

15. just for further info....if you would like it... there is a link in the Training section of firehouse.com titled, "How good is your scene size-up?", which will go into detail about calculating gallonage. It is under III. Fire Conditions > Water requirements.
hope this helps.

16. Jr.
Thanks bro I'll check it out!
Scottsfire

17. Originally posted by SpartanGuy
If it doesn't make much progress, call in another line of equal or greater size.

Just think and you don't have to play around with any math!
And while you've been wasting water (and if your gpm is not sufficient that is all you will be doing) the building continues to be structurally compromised by fire, that's if the fire doesn't overrun you. You don't take a hachet instead of an axe when you perform forcible entry do you? Take the line that can extinguish the fire the FIRST time.

Sometimes math is good.

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